My friend Kerr MacGregor, who has died aged 70, was Britain's leading solar inventor. His most successful invention was Solartwin, a solar water-heating panel which is freezable, unlike most others. By putting water inside his panel, Kerr dispensed with antifreeze, a viscous and unstable chemical gloop. This meant water could circulate more easily, so that a miniature, highly efficient pump could be used, instead of a big clunker. The pump can be powered by just five watts via a small solar electric panel. More than 5,000 Solartwin installations are in place across the world.

Kerr also invented jokes and whimsies, such as a solar-powered bagpipe. At international conferences, clad in his MacGregor kilt, he would thank his hosts with a broad smile, and pipe the Gay Gordons. At the Patent Office, a tedious technical description of his Thermoscreen – a folding screen heater – is accompanied by a colour photograph revealing that Kerr chose to clad his prototype in tartan.

Kerr was born in Scotland and spent his early childhood in India, followed by boarding school in the UK. He was a polymath with strong interests in Scottish politics, music and travel. Thinking, sitting by the fire stroking his cat, energy, travel, whisky, politics, campaigning, technology, making music, friends and family love all sustained the man. He was immune to both high fashion and consumerism, with the exception of kilts, motorbikes and the latest green-energy gadgets.

Kerr was generous with his talent of communicating technical complexities clearly, simply and widely, and inspired a generation of energy engineering students. He is survived by his wife, Anabel; their children, Kirsty, Eoghann, Ellen and Colin; and their grandchildren, Sorley and Alasdair.